Patent Document 1 describes that (R)-1,1,3-trimethyl-4-aminoindane represented by formula (1)
is a useful synthetic intermediate of an agricultural and horticultural fungicide having a plant disease-control effect and describes, and a production method thereof, which is a method of optically resolving 1,1,3-trimethyl-4-aminoindane (racemate) represented by formula (2)
with D-tartaric acid in methanol. Patent Document 1, however, does not mention addition of water for the production of (R)-1,1,3-trimethyl-4-aminoindane.